Correlation Between Y-Balance Test and Balance, Functional Performance, and Outcome Measures in Patients Following ACL Reconstruction

BACKGROUND: The Y-Balance test (YBT) is commonly used to evaluate balance after anterior cruciate ligament reconstruction (ACLR). However, several studies have also used it as a functional performance test (FPT). PURPOSE: This study aimed to examine the relationship between YBT scores and measures of knee joint laxity, static balance, knee flexor and extensor torque and strength ratio, and FPTs. STUDY DESIGN: Retrospective cohort study. METHODS: Fifty-nine patients who underwent ACLR using hamstring autografts were retrospectively analyzed. The Pearson correlation coefficient was used to determine the strength of the association between scores on the YBT and selected outcomes including laxity measured via the KT-2000 arthrometer, static balance measured via the Biodex Balance System, isokinetic muscle torque and hamstring-to-quadriceps (HQ) ratio, and performance on the single leg hop test and the single leg vertical jump test. RESULTS: Forty-six men and 13 women were included. The mean age and follow-up period were 29.6 ± 9.6 years and 12.4 ± 2.1 months, respectively. The KT-2000 arthrometer measures, Biodex Balance System scores, and HQ ratio measurements were not significantly correlated with the YBT scores. All YBT scores, except the YBT-anterior score, correlated with the isokinetic extensor and flexor torques (r-values: 0.271–0.520). All the YBT scores had significant weak to moderate correlations with the single leg hop test and single leg vertical jump test scores: YBT-anterior (r = 0.303, r = 0.258), YBT-posteromedial (r = 0.475, r = 0.412), YBT-posterolateral (r = 0.525, r = 0.377), and YBT-composite (r = 0.520, r = 0.412). CONCLUSION: Post-ACLR YBT scores correlated with functional performance and muscle strength, but not with static balance, joint laxity, and HQ ratios. The YBT scores as a measure of balance are related to improved functional performance and isokinetic torque measures. LEVEL OF EVIDENCE: 3